The present invention relates generally to cutting inserts and, more particularly, to families of cutting inserts usable in the same toolholders.
In milling cutting operations, use of an insert of circular shape permits providing a depth of cut equal to one half of insert diameter, or generating a radius at the bottom of a workpiece. The leading angle of a milling cutting tool with a circular insert depends on depth of cut. The higher the depth of cut is, the higher the leading angle is. To reach the maximum material removal rate using circular inserts, the conventional strategy is to machine with high depth and avoid reaching a high feed per tooth. This strategy tends to create high radial cutting forces which are acceptable when the tool overhang is short but which create chatter effects when total tool length becomes large.
With a high feed insert, such as an insert having four cutting edges, the maximum depth of cut is reduced due to the insert shape and, consequently, the leading angle is reduced. To reach the maximum material removal rate using a high feed insert, the strategy differs from that used with circular inserts. Because the leading angle and depth of cut is typically reduced in a multi-edge insert relative to a circular insert, the feed per tooth can be increased. This strategy tends to reduce radial cutting forces (at least relative to high depth of cut and/or high leading angle operations), which can be a benefit when long overhang is necessary.
When using a finishing insert, the depth of cut and the leading angle are generally reduced further, and feed rate can be increased further.
When switching from use of one type of insert to another, it is ordinarily necessary to adjust various settings on the CNC machine to account for different lengths and diameters of the cutting tool. It is desirable to provide a milling toolholder on which several different kinds of inserts could be mounted for operations such as copy milling, face milling, plunging, helical interpolation, and the like. It is also desirable to provide inserts that can be mounted on the same toolholder so that, regardless which insert is mounted on the toolholder, the tool will generate the same diameter and have the same length.
According to an aspect of the present invention, a family of cutting inserts comprises a plurality of different inserts, each having a different geometry, wherein each insert of the plurality of different inserts is adapted to be mounted in a common insert-receiving pocket on a toolholder of a milling cutting tool so that an outer diameter generated by the milling cutting tool is the same, regardless which insert of the plurality of inserts is mounted in the pocket.
According to another aspect of the present invention, a family of cutting inserts is provided. Each cutting insert in the family has a bottom supporting surface and an axis of rotation and, arranged around the axis of rotation, a plurality of side insert supporting surfaces and a plurality of cutting edge portions corresponding to each of the plurality of side insert supporting surfaces. The cutting edge portions for each insert being generally convex and the cutting edge portions for at least some different inserts in the family having different curvatures. For each cutting edge, a first plane parallel to the axis of rotation and tangent to the cutting edge at a face contact point on the cutting edge is disposed at a predetermined distance from a parallel second plane extending through the axis of rotation and rotated at a predetermined angle relative to a third plane intersecting a corresponding side insert supporting surface along a line substantially perpendicular to the axis of rotation.
According to another aspect of the present invention, a milling cutting tool arrangement is provided and comprises a toolholder comprising a body and at least one insert-receiving pocket in the body, the at least one insert-receiving pocket being adapted to receive any one of a family of cutting inserts.
According to another aspect of the present invention, a cutting insert comprises a plurality of cutting edges and a plurality of corners between the cutting edges, each cutting edge lying along an arc of a respective circle, a first line extending through a centerpoint of a respective one of the cutting edges and a radial center of the respective circle of the respective one of the cutting edges forming a non-zero angle with a second line extending through the centerpoint of the respective one of the cutting edges and a center of rotation of the insert.